Cryogenic Distillation Column Research Articles

The DarkSide-20k underground argon procurement chain

The DarkSide-20k experiment searches for dark matter by looking for interactions of WIMPs in a 50-tonnes target of liquid argon using double-phase time projection chamber (TPC) technology. The key component of the experiment is low radioactivity argon depleted in the isotope 39Ar. Unfortunately, 39Ar is naturally present in atmospheric argon and it is constantly produced due to the interaction with cosmic rays. Finding a source of depleted argon was the first step of the Collaboration when it started to size the DarkSide-20k detector.The procurement chain begins with the Urania plant in Colorado, which can produce argon with a purity of 99.99% from a crude CO2 stream extracted from a deep well, at a rate of about 250 kg per day. The plant has already been fabricated while the site is being prepared for installation. After the extraction and purification of 120 t of underground argon (UAr), it will be transported to Sardinia, Italy, where the ARIA plant, consisting of a 350 m cryogenic distillation column, will further remove impurities up to 2 orders of magnitude. The final purity is expected to be 99.9999%. After the ARIA purification stage, the ultra-pure UAr will be delivered to the Laboratori Nazionali del Gran Sasso, L'Aquila, Italy where it will fill the DarkSide-20k TPC.The ARIA plant has already been fully fabricated and is now in the installation phase in a mine shaft. A shorter version, about 26 m high, has been tested over the last three years with very positive results. We were able to measure the separation factor between two isotopes of nitrogen (29N2, 28N2) and three of argon (40Ar, 38Ar, 36Ar) thus validating the capability of performing isotopic distillation with ARIA.

Design and simulation of 30 000 tons per year of cumene plant from natural gas field

Abstract The research considers the design and simulation of 30 000 tons per year of cumene plant using Aspen HYSYS as the simulation tool. The feed (material content) used is the characterized natural gas from Utorogu Gas Field with composition of 0.9019 methane, 0.0694 ethane, 0.0209 propane, 0.00361 n-butane, 0.00414 i-butane, 0.00005 n-pentane and 0.00007 i-pentane. The cumene plant consist of the cryogenic distillation column, de-hydrogenator (Continuous Stirred Tank Reactor), Alkylator (Plug Flow Reactor), storage tanks, separators, pumps, heat exchanger and mixers. The size/design models of basic plant units such as de-hydrogenator, alkylator, separators, storage tanks and distillation column were developed using the principles of mass and energy balance. The result of design or size specifications in terms of equipment diameter of basic plant units obtained from HYSYS simulation are 0.8 m and 0.319 m for the cryogenic and cumene columns; 1.931 m, 2.244 m and 1.366 m for the propane, propene and cumene storage tanks; 1.868 m and 2.076 m for the de-hydrogenator and alkylator; 1.931 m and 2.146 m for propene and cumene separators respectively. The power or capacity of propane and propene pumps configured in the plant are 0.02 kW and 0.005 kW respectively. The result of the reactor and distillation column thickness specification to withstand corrosion, pressure or stress during plant operation in terms of cylindrical shell and ellipsoidal doomed head are 17.36 mm and 4.31 mm respectively. The economic evaluation (overall cost) including the cost of utilities, catalyst, operating, and maintenance for entire plant is $ 3.004 M.

Steady-State simulation of cryogenic distillation used for helium isotope separation

Helium-3 (3He) is an invaluable and scarce resource with applications in various scientific and industrial fields. It is typically found mixed with helium- 4(4He) in natural gas and nuclear off-gas, which is industrial source of helium. Therefore, separation of the helium isotope is necessary. Cryogenic distillation is a preferred method of separation due to its higher separation coefficient and processing capacity. In this study, a numerical steady-state simulation of cryogenic distillation column for helium isotope has been conducted using programming. The mathematical model for the equilibrium-state cryogenic distillation process was established and solutions of the thermodynamic formulation was proposed. The simulation provided the distribution of 3He and 4He along each distillation column as well as the profiles of temperature and flow rates along the column, based on the designed specifications including the composition of the feeding mixture, feed flow rate and pressure. The required heat duty of the condenser and reboiler was also calculated, and the column dimensions were estimated. Besides, we have studied the effects of the reflux ratio and feed concentration of 3He on the final isotopic contents of the top and bottom products. The results demonstrated that the distillation simulation could provide crucial theoretical support for the smooth execution of future laboratory experiments.

Experimental evaluation of the performance of a cryogenic distillation system under offshore conditions

Cryogenic distillation is the most widely-used industrial method to produce liquid oxygen with high-purity. However, the distillation process in the sieve tray column is very sensitive to tilting and swing, which limits the application of cryogenic air-separation in marine and offshore infrastructures. In this paper, a small air-separation plant with dual-column distillation process was proposed to improve the distillation performance under the offshore conditions, and experiments were carried out under standard (no-tilting and stationary), tilting and swing conditions. A reduction factor of overall section efficiency is proposed to evaluate the influence of offshore conditions on the system performance. The results indicate that sieve tray column can maintain the distillation purity to a certain extent under offshore conditions within the range of 6° tilting and ±10° swing amplitude. Under severe tilting (6°) and swing (±10°-amplitude&11 s-period) conditions, the reduction factors were reduced to 0.592 and 0.590, respectively. Based on the experimental results, two correlations are presented to predict the reduction factor of section efficiency under different tilting angle and swing parameters, respectively, which provide engineering guidance for the design of cryogenic distillation column for offshore applications.

Numerical analysis of the influence of packing corrugation angle on the flow and mass transfer characteristics of cryogenic distillation

The corrugation angle of structured packing is an important structural parameter that affects the mass transfer efficiency and pressure drop of distillation process. However, at present, the detailed effects of corrugation angle on the distillation performance of the cryogenic fluids are seldom reported due to the difficulties in conducting cryogenic experiment, which needs to be further revealed for the optimizing of cryogenic structured packing. In this work, a three-dimensional CFD model combing VOF method was established to investigate the flow characteristics of LOX in Mellapak 250 packing under different packing corrugation angles. The effects of corrugation angle on the component mass transfer rate of cryogenic fluids of oxygen and nitrogen were analyzed in detail. Results show that under the combined action of interfacial area, liquid film thickness and liquid residence time, the mass transfer rate decreases by about 30% with the increase of angle from 45° to 60°, while the decrease of wet pressure drop can reach 81.1%, much higher than the reduction ratio of mass transfer rate. It shows 60° packing has application potential and can be used in the middle part of the cryogenic distillation column where mass transfer force is very large, reducing pressure drop loss without substantially sacrificing mass transfer efficiency. 60° packing with higher specific area can also be applied. In addition, it is found that 50° packing can greatly reduce the loss of pressure drop (41.1%) with only a small amount of mass transfer rate loss (8.8%), which shows a good application prospect in cryogenic distillation.

Additively manufactured cryogenic microchannel distillation device for air separation

AbstractThe efficiency of air separation is tested using three different small‐scale cryogenic distillation columns. The performance of a random packed column is compared to the performance of two microchannel distillation (MCD) columns that use thin wicking structures and gas flow channels to achieve process intensification. The MCD columns tested include a plate‐type layered column and an additively manufactured porous honeycomb (AMPH) column. For columns with 25.4 cm of active height and run under similar conditions, the packed, plate‐type layering, and AMPH columns achieved approximate height equivalent of a theoretical plate (HETP) values of 5.5, 3.7, and 3.2 cm for nitrogen, and 5.9, 4.9, and 3.3 cm for argon. The AMPH column can produce up to 0.4 SLM of more than 90% purity oxygen with 12 W of cooling lift. These results demonstrate the feasibility of using additive manufacturing to construct MCD devices and pave a way for constructing novel MCD designs.

Application and modeling of an online distillation method to reduce krypton and argon in XENON1T

Abstract A novel online distillation technique was developed for the XENON1T dark matter experiment to reduce intrinsic background components more volatile than xenon, such as krypton or argon, while the detector was operating. The method is based on a continuous purification of the gaseous volume of the detector system using the XENON1T cryogenic distillation column. A krypton-in-xenon concentration of (360±60)ppq was achieved. It is the lowest concentration measured in the fiducial volume of an operating dark matter detector to date. A model was developed and fit to the data to describe the krypton evolution in the liquid and gas volumes of the detector system for several operation modes over the time span of 550 days, including the commissioning and science runs of XENON1T. The online distillation was also successfully applied to remove 37Ar after its injection for a low energy calibration in XENON1T. This makes the usage of 37Ar as a regular calibration source possible in the future. The online distillation can be applied to next-generation LXe TPC experiments to remove krypton prior to, or during, any science run. The model developed here allows further optimization of the distillation strategy for future large scale detectors.

Data-Driven Nonlinear Model Reduction Using Koopman Theory: Integrated Control Form and NMPC Case Study

We use Koopman theory for data-driven model reduction of nonlinear dynamical systems with controls. We propose generic model structures combining delay-coordinate encoding of measurements and full state decoding to integrate reduced Koopman modeling and state estimation. We present a deep-learning approach to train the proposed models. A case study demonstrates that our approach provides accurate control models and enables real-time capable nonlinear model predictive control of a high-purity cryogenic distillation column.

Effect of the demethanizer improved control strategy on the separation train for the NGL separation process

In recent years the attention on natural gas production and utilization is growing due to different fundamental aspects. First, the availability of natural gas has increased thanks to technological improvements in the extraction techniques that have made possible the production from unconventional reservoirs. Second, the interest in clean energy is growing, aiming to reduce CO2 emission and thus global warming. Natural gas is a cleaner fossil fuel compared with other traditional energy sources such as oil and coal. Another reason that drives the attention on this fossil fuel is the increasing economic interest of recovering the heavier hydrocarbon fractions contained in it. The fractionation of natural gas liquids (NGL) is an energy-demanding process, often conducted with a separation train that includes cryogenic distillation columns. This work is intended to show how to achieve an energy-efficient recovery of NGLs with a proper control strategy and without composition analyzers. In particular, the effects of a combined cascade control with boilup approximation plus a pressure compensator control for the demethanizer section, on the desired NGL extraction product targets are investigated and compared under feed flowrate disturbances with conventional direct temperature controllers. Overall, it is shown that the cascade control plus pressure compensator provides the best performance and the lowest energy consumption.

Measurement of the underground argon radiopurity for Dark Matter direct searches

A major worldwide effort is underway to procure the radiopure argon needed for DarkSide-20k (DS-20k), the first large scale detector of the new Global Argon Dark Matter Collaboration. The Urania project will extract and purify underground argon (UAr) from CO2 wells in the USA at a production rate of about 330 kg/day. Additional chemical purification of the UAr will be required prior to its use in the DS-20k LAr-TPC. The Aria project will purify UAr using a cryogenic distillation column (Seruci-I), located in Sardinia (Italy). Assessing the UAr purity in terms of 39Ar is crucial for the physics program of the DarkSide-20k experiment. DArT is a small (1 litre) radiopure chamber that will measure the 39 Ar depletion factor in the UAr. The detector will be immersed in the active liquid Ar volume of ArDM (LSC, Spain), which will act as a veto for gammas from the detector materials and the surrounding rock. In this article, the status and prospects of the UAr projects for DarkSide-20k are reviewed with a special focus in DArT.

Design study of a cryogenic distillation column for hydrogen isotope separation system

This paper presents a design study of a cryogenic distillation column for hydrogen isotope separation. The column was modeled as a theoretical equilibrium-based stage column. Thermodynamic properties were evaluated with the Peng–Robinson Twu equation of state model. The liquid holdup and pressure drop of each theoretical stage were modeled with a general packed column model. The models were implemented in an equation-oriented optimization framework. The effects of parameters such as the number of theoretical stages, feed location, diameter, flow rate of the distillate, and condenser duty on the tritium inventory, total pressure drop, and product quality were investigated. An optimal design that minimizes the total amount of tritium in the liquid holdup under a tritium product quality constraint and non-flooding constraints is presented.

PRELIMINARY DEVELOPMENT OF A CONCEPTUAL MODEL OF MATRIX HEAT EXCHANGER

While the basic principles of thermodynamics have remained the same, the necessity for heat exchangers to have good effectiveness in a small volume is constantly growing. Heat exchangers type Matrix Heat Exchanger (MHE), which can meet these requirements, does not have an optimal design variant for its use. These heat exchangers have been approached for 60 years, by many researchers, currently offering only an overview of the process. The mechanism of heat transfer in a matrix heat exchanger is complex, having three different thermal convection paths as well as thermal conduction through two different surfaces. This paper presents the simulations performed in ANSYS Workbench, combining all these heat transfer modes, for developing an optimal model of a perforated plate matrix heat exchanger, used for the pre-cooling of a hydrogen isotopes stream mixture, for purification purposes, as well as, for preparing the inlet temperature in cryogenic distillation columns of hydrogen isotopes.

Separating {^{39}hbox {Ar}} from {^{40}hbox {Ar}} by cryogenic distillation with Aria for dark-matter searches

Aria is a plant hosting a {350},hbox {m} cryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of {^{39}hbox {Ar}} in argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed, {^{39}hbox {Ar}} is a beta -emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant.

Dynamic simulation tools for isotopic separation system modeling and design

Cryogenic distillation is the best candidate for hydrogen isotopic separation in fusion power plants. The design of the ITER's Isotope Separation System can still undergo major changes due to its close contact with the Water Detritiation System and this will be decisive in the design of future DEMO detritiation facilities. Dynamic simulation tools are key in the analysis and design of tritium processing systems and the use of commercial simulators can be especially valuable to this end and may add capabilities in terms of standardization of industrial-scale fusion plant modeling and conjunction of operator training systems, human-machine interface and process monitoring and control. The present work proposes the use of a commercial dynamic process simulator such as Aspen HYSYS given its abilities to overcome the challenges described. This document presents the implementation of a cryogenic distillation column in Aspen HYSYS by setting the thermodynamic principles upon which the simulation is founded and verifying isotopic separation models with experimental data available in the literature.

Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis

Cryogenic air separation processes are widely used for the large-scale production of nitrogen and oxygen. The most widely used design for this process involves two distillation columns operating at different pressures. This work focuses on the selection of suitable cryogenic air separation process by evaluating seven alternative designs of the two-column air separation process based on detailed exergy analysis. The feed conditions (500 tons/h, and 50% relative humidity of air), product purities (99 mole% for both nitrogen and oxygen), and operational conditions (pressures of both distillation columns) are kept same in all designs. The two cryogenic distillation columns in each configuration are heat-integrated to eliminate the need for external utilities. Steady-state simulation results are used to calculate the exergy efficiency (%) of each equipment as well as its contribution toward the overall exergy destruction rate (kW) of the process. The results show that the compression section is a major source of exergy destruction, followed by the low-pressure column, and the multi-stream heat exchanger. A Petlyuk-like configuration, labeled as C1, provides the lowest exergy destruction rate.

Dynamic behavior and control strategy of cryogenic distillation column for hydrogen isotope separation in CFETR

Cryogenic distillation is one of the key processes to separate and concentrate tritium in the tritium fuel cycle of fusion reactors. The dynamic behavior and control strategy of the cryogenic distillation column in China Fusion Engineering Test Reactor was investigated by Aspen Dynamics. Six control models were applied to resist the disturbance of feed flow or feed composition fluctuation during operation. The dynamic simulation results indicated that the control structure of cascade composition/temperature combined with reboiler duty/feed flow rate ratios had the best dynamic performance. When the feed flow fluctuated, the purities of the bottom and top products were maintained in 1.5 h and 4 h, respectively. When the feed composition fluctuated, the purities of the bottom and top products were maintained in 2.5 h and 4 h, respectively.

Optimization of 13C enrichment by carbon monoxide cryogenic distillation

The main purpose of this study is the optimization of the operating mode for cryogenic distillation columns that provide an isotopic enrichment in stable isotopes. The analysis is based on an experimental cycle for 13C enrichment by CO cryogenic distillation conducted in semi-batch mode in the column of the National Institute for Research and Development of Isotopic and Molecular Technologies. The experimental run is reproduced closely using the simulation software ProSim-BatchColumn, applied for the first time to this type of separations. It is, then, used to investigate the dynamics of the process and the effect of the feed flowrate on the separation to be achieved. As a result, an optimized cycle is proposed, which allows reaching the desired specifications in around one-third the time. The obtained results are interesting and can be applied to all the mixtures where heavy components have a higher commercial value than the light ones.

Study of dry ice formation during blowdown of CO₂-CH₄ from cryogenic distillation column

Cryogenic distillation columns are generally subjected to high-pressure loadings during the natural gas purification process. The high-pressure conditions inside the column cause safety risk e.g. rupture. When an emergency arises, blowdown is a typical way of minimizing the failure hazard. However, blowdown at the cryogenic conditions involves dry ice formation due to the rapid decrease in temperature driven by the Joule-Thomson effect. The dry ice formation intensifies the failure hazard due to the orifice blockage. Therefore, optimization of blowdown parameters is necessary to avoid the dry ice formation. So far, very limited studies are available in the literature for the blowdown of CO₂-CH₄ mixture, especially at the cryogenic conditions. In this study, a computational investigation followed by the experimental validation is accomplished to analyze the dry ice formation during blowdown of CO₂-CH₄ binary mixture from the cryogenic distillation column. The composition of mixture, orifice size, and initial conditions inside vessel have a high impact on blowdown path. A 3.00 mm orifice is the most suitable size for the blowdown at cryogenic conditions as it doesn't promote solidification and discharges the inventory quickly. Based on the experimental observation, an empirical correlation is also developed to instantly find out the optimum blowdown parameters.

Rigorous Dynamic Simulation of Cryogenic Distillation of Hydrogen Isotopologues in the Fuel Cycle of a Thermonuclear Reactor Based on UV Flash

Operation of the fuel cycle of a thermonuclear fusion reactor naturally leads to accumulation of surplus protium, but in some cases it can also lead to accumulation of surplus deuterium. Both surplus protium and deuterium have to be separated, detritiated, and discharged to the environment, normally passing a final detritiation stage based on either the liquid phase catalytic exchange or water distillation process. The concept of a multicolumn cryogenic distillation (CD) system capable of discharging a time-varying surplus of deuterium is presented in this paper. A model of a CD column based on a UV (internal energy U – volume V) flash formulation and equation of state (EOS) thermodynamic model for hydrogen isotopologue mixtures is also presented at the principal step to a comprehensive model of the isotope separation system. Although fundamental for constant volume systems, the UV formulation of the thermodynamic state has not been widely used in transient simulations; in particular, for distillation dynamics modeling, other approaches are much more common. At the same time, in helium cryogenics the UV formulation has gained wide usage in large-scale dynamic simulations. It is known from the literature that a UV formulation of the distillation problem is very challenging for a numerically stable implementation. To cope with this situation, we present our findings on the sources of numerical instabilities and approaches.

High-pressure cryogenic distillation data for improved LNG production

Current methods and models to reliably simulate and predict cryogenic column performance, essential for designing and operating commercial Liquefied Natural Gas (LNG) distillation and scrub columns, are currently lacking accurate and reliable empirical data at industrially-relevant conditions (high pressure/low temperature). This leads to conservative design for safety purposes. This paper endeavours to address this gap. Through the use of a unique cryogenic distillation column, critical experimental data at industry-relevant conditions (up to 4 MPa and down to 233 K) have been collected. This constitutes an essential step towards future optimization of LNG scrub columns, eliminating the requirement for over-design, thus improving production and reducing costs. The experimental data were compared with the predictions of the steady state model and showed reasonable agreement, although discrepancies were observed, confirming the need to improve models of LNG scrub columns.